Section 6.3 & 6.4 - ABS & coupling and uncoupling

1. 6.1 Antilock Brake Systems
6.1.1 – Trailers Required to Have ABS
All trailers and converter dollies built on or after March 1, 1998, are required to
have ABS. However, many trailers and converter dollies built before this date
have been voluntarily equipped with ABS.
Trailers will have yellow ABS malfunction lamps on the left side, either on the
front or rear corner. See Figure 6.7. Dollies manufactured on or after March 1,
1998, are required to have a lamp on the left side.
In the case of vehicles manufactured before the required date, it may be
difficult to tell if the unit is equipped with ABS. Look under the vehicle for the
ECU and wheel speed sensor wires coming from the back of the brakes.

2. 6.2.6 Braking with ABS
ABS is an addition to your normal
brakes. It does not decrease or
increase your normal braking capability.
ABS only activates when wheels are
about to lock up.
ABS does not necessarily shorten your
stopping distance, but it does help you
keep the vehicle under control during
hard braking.

3. ABS helps you avoid wheel lock up. The computer senses impending lockup,
reduces the braking pressure to a safe level, and you maintain control.
Having ABS on only the trailer, or even on only one axle, still gives you more
control over the vehicle during braking.
When only the trailer has ABS, the trailer is less likely to swing out, but if you
lose steering control or start a tractor jackknife, let up on the brakes (if you
can safely do so) until you gain control.
When you drive a tractor-trailer combination with ABS, you should brake as
you always have. In other words:
Use only the braking force necessary to stop safely and stay in control.
Brake the same way, regardless of whether you have ABS on the tractor, the
trailer, or both.

4. As you slow down, monitor your tractor and trailer and back off the brakes (if
it is safe to do so) to stay in control.
Remember, if your ABS malfunctions, you still have regular brakes. Drive
normally, but get the system serviced soon.
ABS won’t allow you to drive faster, follow more closely, or drive less
carefully.
6.3 – Coupling and Uncoupling
Knowing how to couple and uncouple correctly is basic to safe operation of
combination vehicles. Wrong coupling and uncoupling can be very
dangerous. General coupling and uncoupling steps are listed below. There
are differences between different rigs, so learn the details of coupling and
uncoupling the truck(s) you will operate.

5. 6.3.1 – Coupling Tractor-Semitrailers
Step 1. Inspect Fifth Wheel
Check for damaged/missing parts.
Check to see that mounting to tractor is secure, no cracks in frame, etc.
Be sure that the fifth wheel plate is greased as required. Failure to keep the
fifth wheel plate lubricated could cause steering problems because of friction
between the tractor and trailer.
Check if fifth wheel is in proper position for coupling:
Wheel tilted down toward rear of tractor.

6. Jaws open.
Safety unlocking handle in the automatic lock position.
If you have a sliding fifth wheel, make sure it is locked.
Make sure the trailer kingpin is not bent or broken.
Step 2. Inspect Area and Chock Wheels
Make sure area around the vehicle is clear.
Be sure trailer wheels are chocked or spring brakes are on.
Check that cargo (if any) is secured against movement due to tractor being
coupled to the trailer.
Step 3. Position Tractor
Put the tractor directly in front of the trailer. (Never back under the trailer at
an angle because you might push the trailer sideways and break the landing
gear.)
Check position, using outside mirrors, by looking down both sides of the

7. Step 4. Back Slowly
Back until fifth wheel just touches the trailer. Don't hit the trailer.
Step 5. Secure Tractor Put on the parking brake. Put transmission in neutral.
Step 6. Check Trailer Height
The trailer should be low enough that it is raised slightly by the tractor when
the tractor is backed under it. Raise or lower the trailer as needed. (If the
trailer is too low, the tractor may strike and damage the trailer nose; if the
trailer is too high, it may not couple correctly.)
Check that the kingpin and fifth wheel are aligned.

8. Step 7. Connect Air-lines to Trailer
Check glad hand seals and connect tractor emergency air-line to trailer
emergency glad hand.
Check glad hand seals and connect tractor service air-line to trailer service
glad hand.
Make sure air-lines are safely supported where they won't be crushed or
caught while tractor is backing under the trailer.
Step 8. Supply Air to Trailer
From cab, push in "air supply" knob or move tractor protection valve control
from the "emergency" to the "normal" position to supply air to the trailer brake
system.
Wait until the air pressure is normal. Check brake system for crossed air-
lines.
Shut engine off so you can hear the brakes.

9. Apply and release trailer brakes and listen for sound of trailer brakes being
applied and released. You should hear the brakes move when applied and air
escape when the brakes are released.
Check air brake system pressure gauge for signs of major air loss.
When you are sure trailer brakes are working, start engine.
Make sure air pressure is up to normal.
Step 9. Lock Trailer Brakes
Pull out the "air supply" knob or move the tractor protection valve control from
"normal" to "emergency."
Step 10. Back Under Trailer
Use lowest reverse gear.
Back tractor slowly under trailer to avoid hitting the kingpin too hard.
Stop when the kingpin is locked into the fifth wheel.

10. Step 11. Check Connection for Security
Raise trailer landing gear slightly off ground.
Pull tractor gently forward while the trailer brakes are still locked to check that
the trailer is locked onto the tractor.
Step 12. Secure Vehicle Put transmission in neutral. Put parking brakes on.
Shut off engine and take key with you so someone else won't move truck
while you are under it.
Step 13. Inspect Coupling
Use a flashlight, if necessary.
Make sure there is no space between upper and lower fifth wheel. If there is
space, something is wrong (kingpin may be on top of the closed fifth wheel
jaws, and trailer would come loose very easily).

11. Go under trailer and look into the back of the fifth wheel. Make sure the fifth
wheel jaws have closed around the shank of the kingpin.
Check that the locking lever is in the "lock" position.
Check that the safety latch is in position over locking lever. (On some fifth
wheels the catch must be put in place by hand.)
If the coupling isn't right, don't drive the coupled unit; get it fixed.
Step 14. Connect the Electrical Cord and Check Air-lines
Plug the electrical cord into the trailer and fasten the safety catch.
Check both air-lines and electrical line for signs of damage.
Make sure air and electrical lines will not hit any moving parts of vehicle.
Step 15. Raise Front Trailer Supports (Landing Gear)
Use low gear range (if so equipped) to begin raising the landing gear. Once
free of weight, switch to the high gear range.

12. Raise the landing gear all the way up. (Never drive with landing gear only
part way up as it may catch on railroad tracks or other things.)
After raising landing gear, secure the crank handle safely.
When full weight of trailer is resting on tractor:
Check for enough clearance between rear of tractor frame and landing gear.
(When tractor turns sharply, it must not hit landing gear.)
Check that there is enough clearance between the top of the tractor tires and
the nose of the trailer.
Step 16. Remove Trailer Wheel Chocks
Remove and store wheel chocks in a safe place.
6.3.2 – Uncoupling Tractor-Semitrailers
The following steps will help you to uncouple safely.

13. Step 1. Position Rig
Make sure surface of parking area can support weight of trailer.
Have tractor lined up with the trailer. (Pulling out at an angle can damage
landing gear.)
Step 2. Ease Pressure on Locking Jaws
Shut off trailer air supply to lock trailer brakes.
Ease pressure on fifth wheel locking jaws by backing up gently. (This will help
you release the fifth wheel locking lever.)
Put parking brakes on while tractor is pushing against the kingpin. (This will
hold rig with pressure off the locking jaws.)
Step 3. Chock Trailer Wheels
Chock the trailer wheels if the trailer doesn't have spring brakes or if you're
not sure. (The air could leak out of the trailer air tank, releasing its emergency
brakes. Without chocks, the trailer could move.)

14. Step 4. Lower the Landing Gear
If trailer is empty, lower the landing gear until it makes firm contact with the
ground.
If trailer is loaded, after the landing gear makes firm contact with the ground,
turn crank in low gear a few extra turns. This will lift some weight off the
tractor. (Do not lift trailer off the fifth wheel.) This will:
Make it easier to unlatch fifth wheel. Make it easier to couple next time.
Step 5. Disconnect Air-lines and Electrical Cable
Disconnect air-lines from trailer. Connect air-line glad hands to dummy
couplers at back of cab or couple them together.
Hang electrical cable with plug down to prevent moisture from entering it.
Make sure lines are supported so they won't be damaged while driving the
tractor.

15. Step 6. Unlock Fifth Wheel
Raise the release handle lock.
Pull the release handle to "open" position.
Keep legs and feet clear of the rear tractor wheels to avoid serious injury in case
the vehicle moves.
Step 7. Pull Tractor Partially Clear of Trailer
Pull tractor forward until fifth wheel comes out from under the trailer.
Stop with tractor frame under trailer (prevents trailer from falling to ground if
landing gear should collapse or sink).

16. Apply parking brake.
Place transmission in neutral.
Step 9. Inspect Trailer Supports
Make sure ground is supporting trailer. Make sure landing gear is not damaged.
Step 10. Pull Tractor Clear of Trailer
Release parking brakes.
Check the area and drive tractor forward until it clears.